March 21, 2013

Autism Risk Linked To Men Who Father Kids Later In Life

An international team of researchers has found that men who have children later in life are more likely to have grandchildren with autism.

According to the team´s report in JAMA Psychiatry, older men may inadvertently pass on ℠silent mutations´ that increase the risk of disease in their grandchildren. These mutations have no apparent impact on the fathers' own children, but there may be a cumulative interactive effect that could increase the risk of their grandchildren developing the condition.

"We tend to think in terms of the here and now when we talk about the effect of the environment on our genome,” explained study co-author Dr. Avi Reichenberg, from King's College London's Institute of Psychiatry. “For the first time in psychiatry, we show that your father's and grandfather's lifestyle choices can affect you.”

“This doesn't mean that you shouldn't have children if your father was old when he had you, because whilst the risk is increased, it is still small,” Reichenberg said. “However, the findings are important in understanding the complex way in which autism develops."

For the study, the research team culled data from Sweden´s national databases. They studied and tracked the ages of about 6,000 people who were diagnosed with autism and more than 30,000 individuals without the disease.

An analysis of the data showed that men who had a daughter when they were 50 or older were 1.79 times more likely to have a grandchild with autism, compared to men who had children between 20 and 24.

"We know from previous studies that older paternal age is a risk factor for autism,” said lead author Emma Frans, from Karolinska Institutet in Sweden. “This study goes beyond that and suggests that older grandpaternal age is also a risk factor for autism, suggesting that risk factors for autism can build up through generations."

Reichenberg pointed out that while age of a child´s grandparent does appear to increase risk of autism, there are many factors, besides age, that could determine if a child will be autistic.

"Unfortunately we can't put exact figures on this risk yet,” he told the BBC News. “But most children born with older fathers and grandfathers grow up fine.”

"And as scientists this type of information helps open doors to understanding more about the condition,” he added.

Alycia Halladay, a senior director at the advocacy group Autism Speaks who was not involved in the research, praised the study for its thoroughness and innovation.

"This study is important because it utilizes rich datasets with health record information," Halladay told US News. "This approach can open the door for future work on genetic and environmental factors associated with (autism spectrum disorders)."

The JAMA study was published on the same day that the US Centers for Disease Control and Prevention (CDC) issued a report stating that one in every 50 US school children now has an autism spectrum disorder. The ratio is slightly higher from the CDC´s 2007 estimate of one in 88. The government agency said improvements in diagnosis are most likely responsible for the statistical increase.